2000 Volvos S80 misfire

Post by **precopster** » 13 Apr 2015, 14:38

Having a reread over this and thinking aloud.....

The spark plug removal has me thinking the circuit powering the coil packs is compromised. Have you checked voltages at coil packs during engine running?. Something tells me voltage will be low. Trace coil wiring to the apprpriate relay and replace it.

jaru · Post by **jaru** » 13 Apr 2015, 18:56

Today I did the compression test:
cyl1:150psi cyl2:130psi cyl3:120psi cyl4:155 psi cyl5:150 psi and cyl6:150psi.
Are the lower readings on 2 and 3 still acceptable?
When I dropped some oil in cyl 2 and 3 the readings on both came up to 145psi.

Thanks

jaru · Post by **jaru** » 15 Apr 2015, 14:38

Today I checked the voltage to the ignition coils. They all had 14VDC and all plugs have spark.
The new OBDII reader got code P0300 and said car computer has no freeze frame data.
I'm still puzzled that it will start only with one spark plug physically removed. As long the plug is installed with ignition coil removed from it, it will not start either.
I'm kind of thinking that it is a timing issue.

Thanks for any help

Post by **pierremcalpine** » 15 Apr 2015, 14:57

Faulty fuel pressure regulator...could it be that with one plug removed the fuel pressure is on but when the 5th cylinder is connected there is insufficient pressure....I'm totally guessing at that last bit but fuel pressure regs on that vintage do cause a no start condition...

jaru · Post by **jaru** » 15 Apr 2015, 23:04

I kind of doubt that, since I measure 50 psi at the fuel rail. I can also feel the gas being thrown out through the plug hole on what ever cylinder I remove the spark plug.

THAI UNG · Post by **THAI UNG** » 16 Apr 2015, 13:02

Have you ever notice the difference cranking speed between 6cyl.and 5cyl.I think your starter is weak and slow,it couldn't crank fast enough speed to start fully loaded 6cyl.but it could on 1 less load cyl.I could be wrong.Used to get one crank one started, til six months ago took two cranks to start,two months ago three to four time to get it running,one and half month after installed a new starter I'm happy to see one crank one start all over again...

jaru · Post by **jaru** » 16 Apr 2015, 18:22

The cranking speed doesn't change whether I have all plugs installed or only 5 plugs.
Actually it cranks very well. Thanks for your input!

Post by **precopster** » 17 Apr 2015, 07:36

I think there may be coil pack positions swapped during your son's spark plug and coil pack replacement as this is when the problem began.

Get yourself a wiring diagram and make sure that the colors on the coil pack wiring correspond to the ones fitted. See if you can swap 2 or more of the coil packs around with wiring attached and make them still reach the spark plug holes. This happened to me when I owned a 960 and was easy to make this mistake when disconnecting coil packs or doing head work.

jaru · Post by **jaru** » 17 Apr 2015, 20:34

Thanks man, I will check that

jaru · Post by **jaru** » 20 Apr 2015, 21:43

Now I took a strange turn. When putting in different plugs and ignition coils I couldn't get it stated again.
But when I took off the intake manifold I was all of sudden able to start car with all 6 spark plugs.
It would only idle, but didn't die until it loosely put the manifold back in place. I could also see some movement in the ETM, so I think the ETM works. So is the fuel supply the problem?

2000 Volvos S80 misfire

Re: 2000 Volvos S80 misfire